I'm still in the process of breaking in my first custom rifle, a 6.5x55 built on a commercial '98 Mauser action with a premium air guaged 1:8 Douglas barrel and chambered with PT&G's 6.5x55 Match reamer. I started out cleaning after every round for the first 5, then after every 5 round string through the first 50 rounds down the tube. I'm using Outers foaming bore cleaner to get the initial carbon fouling, Montana Extreme Copper Killer, and Kroil. I can definitely see how a guy could be tempted to use the abrasives to speed up the project. Through the second 50 rounds I cleaned after every 10 rounds but now I am just cleaning after each shooting session of 30-50 rounds and have found that it is easier now and faster to clean than it was at any point during the initial 100 rounds and accuracy is pleasing to say the least. I'm using the same cleaning process and finding less fouling and fouling that comes out much easier.

I have a couple of factory rifle as well, neither is new by any means, that I did no break in on whatsoever. Just shot them and cleaned them once a year before putting them away. My question is can I go back now and improve the accuracy of those 2 other rifles by taking them from an absolute clean bore through the breakin process?

I have a couple of factory rifle as well, neither is new by any means, that I did no break in on whatsoever. Just shot them and cleaned them once a year before putting them away. My question is can I go back now and improve the accuracy of those 2 other rifles by taking them from an absolute clean bore through the breakin process?

Well it's a good question so lets talk a little bit about factory barrels.
I have seen very nice, and pretty ugly factory tubes. A bore scope of a new rifle can reviel any gross deficencys in a barrel. I have found the normal reamer marks but also lands completly torn away from what I asume must have been broken tooling, or improper handling at the factory. I also have seen the obvious unconcentric throats and beat up looking crowns. All these things can contribute to poor shooting of a factory barrel. As well as things that are not easily seen such as bore dimensional variences. Break-in may not make a problem barrel shoot any better if there if physical issues with the tube.

Barrel break in is a process that happens regardless of how we treat our barrel. Someone who shoots 100 rounds and then cleans may not be thinking about break in but the process of conditioning is taking place. By doing a shoot and clean we are trying to get the barrel to go into a state of easy cleaning/less fouling quicker than what would occur under normal use. In custom barrels it is much easier because the barrel maker lapped the barrel to a condition that left few to no anomilies in the bore.

So I would say it may be possible for a barrel that fouled from day one, and built up a layer of copper, to be cleaned to barrel steel and "re-broke in" I do not know how effective the results would be but it would not hurt.

One thing I have noticed during my factory rifle days was that most of the guns I had did not shoot there best until they were over 200 rounds fired, and that was after I noticed they started to clean up easier. A Ruger varmit in 22-250 in particular had been a good shooting rifle and I cleaned it about every 20-30 rounds and it always had lots of copper that was a pain to get out. I would guess I was at about 250-300 rounds when all of a sudden it started to clean much easier to the point that I could put over 100 rounds thru her and still have it shooting well. Before that time it had always shot well but not after the fouling built up. My guess is it uniformed and smoothed out to a point that fouling no longer built up as it had. I had not set out to break in this barrel it just happened on it's own.

I just recently had a customer send me 2 used 204 ruger barrels, one a factory savage and the other a shilen. He sent a 20 tactical reamer and wanted the better of the 2 barrels rechmbered/set back. I was thinking well it will be the shilen. Well after the bore scope I picked the savage barrel. It had been shot enough that all the usual tooling/reamer marks present in new savage barrrels were gone and the barrels finish resembled more of a lapped look from the bullets slowly abrading the steel so that the structure of the barrel was parrellel with the lands. The shilen just showed too much erosion for me to feel that it was worth the customers money to mess with. This fellow obviously new how to clean a barrel as no copper was present in either one and the savage barrel did not show any indication of abuse by abrasive paste.

Well the reports were good He was getting groups under .200" and placed 3rd in a local BR match.

Thanks for this great article. I was indeed confused about barrel care as I am new into Long Range Shooting. I have seen no one else sum up the facts in such a logical way. Followed this advice in breaking in my Barrett MRAD and your advice worked to a tee. I am looking forward to years of good shooting.

Thanks for the article. I read it when you first wrote it and it helped turn the light on.

I gave my nephew a Mossberg ATR in .270. I told him that we were going to break in the barrel and he gave me this look like I was talking about a 2 headed snake. After the first shot, he almost had to pound the patch down the bore, it was that tight. We did the 1 and clean for 10, then 3 and clean for 30. By the time the last 3 shots were run thru the tube, he could run the patch thru the tube easily, and it only took 5 patches to clean all the copper out. He's a believer now! We went thru almost 500 patches during the process, but it was worth it. After some load development he's shooting 3/8 moa with it. If it's calm out, and he's shooting from the bench, a 2" gong at 350 yds gets boring.

I've changed the solvents that I've used since you first published the article. Now I'm using Hoppes Elite for the carbon, and Montana Extreme Copper Killer (same as the old BMG50) Those 2 seem to work the best. Nickel plated jags and nylon brushes. I switched to those after chasing my tail for a day only to realize that the "copper" that I was seeing was from the jag/brush.

I came to the same conclusion about break in and use my bore scope to evaluate a barrel
before and after break in. I am not ridged about the number of shoot and cleans I do and because different barrel take different amounts of break in I let the barrel tell me when it is broke in.

Some have shone a marked improvement after 4 or 5 shots and some have taken 20 +shots
to come around. Some factory barrels continue to improve for 50 to 60 rounds. I have never
done over 20 shoot and cleans on these barrels and just go with the 5 shots and clean method.

Breaking in a barrel is a slow process but well worth the time and patience required.